[1/1] Y2038: make __mktime_internal compatible with 64-bit-time

Message ID 20180619121626.24902-2-albert.aribaud@3adev.fr
State New
Headers show
Series
  • Y2038 support batch 2 - __mktime_internal
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Commit Message

Albert ARIBAUD (3ADEV) June 19, 2018, 12:16 p.m.
This implies that its callers be 64-bit-time compatible too.
It is done by creating 64-bit-time versions of these and
turning their original 32-bit-time versions into wrappers
(at a slight execution time cost).

The callers affected are:

      * mktime
      * timelocal (as an alias of mktime)
      * timegm
---
 include/time.h | 12 +++++-----
 time/mktime.c  | 62 +++++++++++++++++++++++++++++++-------------------
 time/timegm.c  | 24 ++++++++++++++-----
 3 files changed, 63 insertions(+), 35 deletions(-)

-- 
2.17.1

Comments

Joseph Myers June 19, 2018, 12:21 p.m. | #1
On Tue, 19 Jun 2018, Albert ARIBAUD (3ADEV) wrote:

>    if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)

>      {

> -      /* time_t isn't large enough to rule out overflows, so check

> -	 for major overflows.  A gross check suffices, since if t0

> +      /* __time64_t is large enough to rule out overflows, but check

> +	 for major overflows anyway.  A gross check suffices, since if t0


Are you sure it's coherent to have code in this file using a TIME_T_MAX 
that's defined in terms of time_t, when the code is using __time64_t?  I'd 
expect you to need to define TIME_T_MAX and TIME_T_MIN in terms of 
__time64_t instead.

> +  __set_errno(EOVERFLOW);


Missing space before '('.  You need to watch out for such issues 
throughout the patch series.

> +  __set_errno(EOVERFLOW);


Likewise.

-- 
Joseph S. Myers
joseph@codesourcery.com
Albert ARIBAUD (3ADEV) June 19, 2018, 4:32 p.m. | #2
Hi Joseph,

On Tue, 19 Jun 2018 12:21:58 +0000, Joseph Myers
<joseph@codesourcery.com> wrote :

> On Tue, 19 Jun 2018, Albert ARIBAUD (3ADEV) wrote:

> 

> >    if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)

> >      {

> > -      /* time_t isn't large enough to rule out overflows, so check

> > -	 for major overflows.  A gross check suffices, since if t0

> > +      /* __time64_t is large enough to rule out overflows, but check

> > +	 for major overflows anyway.  A gross check suffices, since if t0  

> 

> Are you sure it's coherent to have code in this file using a TIME_T_MAX 

> that's defined in terms of time_t, when the code is using __time64_t?  I'd 

> expect you to need to define TIME_T_MAX and TIME_T_MIN in terms of 

> __time64_t instead.


You're right, but it's actually worse than that :( I've used the wrong
local branch in creating this patch set. This one was taken halfway back
into the code and a lot of time_t are still in there. Apologies, will
re-post the right one as v2 as soon as I've proofread it.

> > +  __set_errno(EOVERFLOW);  

> 

> Missing space before '('.  You need to watch out for such issues 

> throughout the patch series.

> 

> > +  __set_errno(EOVERFLOW);  

> 

> Likewise.


Will fix.

Cordialement,
Albert ARIBAUD
3ADEV

Patch

diff --git a/include/time.h b/include/time.h
index eaec898fac..8c261abcf4 100644
--- a/include/time.h
+++ b/include/time.h
@@ -50,13 +50,13 @@  extern void __tzset_parse_tz (const char *tz) attribute_hidden;
 extern void __tz_compute (__time64_t timer, struct tm *tm, int use_localtime)
   __THROW attribute_hidden;
 
-/* Subroutine of `mktime'.  Return the `time_t' representation of TP and
-   normalize TP, given that a `struct tm *' maps to a `time_t' as performed
+/* Subroutine of `mktime'.  Return the `__time64_t' representation of TP and
+   normalize TP, given that a `struct tm *' maps to a `__time64_t' as performed
    by FUNC.  Keep track of next guess for time_t offset in *OFFSET.  */
-extern time_t __mktime_internal (struct tm *__tp,
-				 struct tm *(*__func) (const time_t *,
-						       struct tm *),
-				 time_t *__offset) attribute_hidden;
+extern __time64_t __mktime_internal (struct tm *__tp,
+				     struct tm *(*__func) (const __time64_t *,
+							   struct tm *),
+				     __time64_t *__offset) attribute_hidden;
 
 /* nis/nis_print.c needs ctime, so even if ctime is not declared here,
    we define __ctime64 as ctime so that nis/nis_print.c can get linked
diff --git a/time/mktime.c b/time/mktime.c
index 5f038a212f..640f4f326e 100644
--- a/time/mktime.c
+++ b/time/mktime.c
@@ -35,6 +35,7 @@ 
 #include <time.h>
 
 #include <limits.h>
+#include <errno.h>
 
 #include <string.h>		/* For the real memcpy prototype.  */
 
@@ -277,15 +278,15 @@  time_t_int_add_ok (time_t a, int b)
    If TP is null, return a value not equal to *T; this avoids false matches.
    If overflow occurs, yield the minimal or maximal value, except do not
    yield a value equal to *T.  */
-static time_t
+static __time64_t
 guess_time_tm (long_int year, long_int yday, int hour, int min, int sec,
-	       const time_t *t, const struct tm *tp)
+	       const __time64_t *t, const struct tm *tp)
 {
   if (tp)
     {
-      time_t d = ydhms_diff (year, yday, hour, min, sec,
-			     tp->tm_year, tp->tm_yday,
-			     tp->tm_hour, tp->tm_min, tp->tm_sec);
+      __time64_t d = ydhms_diff (year, yday, hour, min, sec,
+				 tp->tm_year, tp->tm_yday,
+				 tp->tm_hour, tp->tm_min, tp->tm_sec);
       if (time_t_add_ok (*t, d))
 	return *t + d;
     }
@@ -304,17 +305,17 @@  guess_time_tm (long_int year, long_int yday, int hour, int min, int sec,
    If *T is out of range for conversion, adjust it so that
    it is the nearest in-range value and then convert that.  */
 static struct tm *
-ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
-		time_t *t, struct tm *tp)
+ranged_convert (struct tm *(*convert) (const __time64_t *, struct tm *),
+		__time64_t *t, struct tm *tp)
 {
   struct tm *r = convert (t, tp);
 
   if (!r && *t)
     {
-      time_t bad = *t;
-      time_t ok = 0;
+      __time64_t bad = *t;
+      __time64_t ok = 0;
 
-      /* BAD is a known unconvertible time_t, and OK is a known good one.
+      /* BAD is a known unconvertible __time64_t, and OK is a known good one.
 	 Use binary search to narrow the range between BAD and OK until
 	 they differ by 1.  */
       while (bad != ok + (bad < 0 ? -1 : 1))
@@ -346,12 +347,12 @@  ranged_convert (struct tm *(*convert) (const time_t *, struct tm *),
    compared to what the result would be for UTC without leap seconds.
    If *OFFSET's guess is correct, only one CONVERT call is needed.
    This function is external because it is used also by timegm.c.  */
-time_t
+__time64_t
 __mktime_internal (struct tm *tp,
-		   struct tm *(*convert) (const time_t *, struct tm *),
-		   time_t *offset)
+		   struct tm *(*convert) (const __time64_t *, struct tm *),
+		   __time64_t *offset)
 {
-  time_t t, gt, t0, t1, t2;
+  __time64_t t, gt, t0, t1, t2;
   struct tm tm;
 
   /* The maximum number of probes (calls to CONVERT) should be enough
@@ -382,7 +383,7 @@  __mktime_internal (struct tm *tp,
 
   /* The other values need not be in range:
      the remaining code handles minor overflows correctly,
-     assuming int and time_t arithmetic wraps around.
+     assuming int and __time64_t arithmetic wraps around.
      Major overflows are caught at the end.  */
 
   /* Calculate day of year from year, month, and day of month.
@@ -393,7 +394,7 @@  __mktime_internal (struct tm *tp,
   long_int lmday = mday;
   long_int yday = mon_yday + lmday;
 
-  time_t guessed_offset = *offset;
+  __time64_t guessed_offset = *offset;
 
   int sec_requested = sec;
 
@@ -415,8 +416,8 @@  __mktime_internal (struct tm *tp,
 
   if (TIME_T_MAX / INT_MAX / 366 / 24 / 60 / 60 < 3)
     {
-      /* time_t isn't large enough to rule out overflows, so check
-	 for major overflows.  A gross check suffices, since if t0
+      /* __time64_t is large enough to rule out overflows, but check
+	 for major overflows anyway.  A gross check suffices, since if t0
 	 has overflowed, it is off by a multiple of TIME_T_MAX -
 	 TIME_T_MIN + 1.  So ignore any component of the difference
 	 that is bounded by a small value.  */
@@ -533,7 +534,7 @@  __mktime_internal (struct tm *tp,
 	for (direction = -1; direction <= 1; direction += 2)
 	  if (time_t_int_add_ok (t, delta * direction))
 	    {
-	      time_t ot = t + delta * direction;
+	      __time64_t ot = t + delta * direction;
 	      struct tm otm;
 	      ranged_convert (convert, &ot, &otm);
 	      if (! isdst_differ (isdst, otm.tm_isdst))
@@ -575,11 +576,11 @@  __mktime_internal (struct tm *tp,
    offset in seconds.  'int' should be good enough for GNU code.  We
    can't fix this unilaterally though, as other modules invoke
    __mktime_internal.  */
-static time_t localtime_offset;
+static __time64_t localtime_offset;
 
 /* Convert *TP to a time_t value.  */
-time_t
-mktime (struct tm *tp)
+__time64_t
+__mktime64 (struct tm *tp)
 {
 #ifdef _LIBC
   /* POSIX.1 8.1.1 requires that whenever mktime() is called, the
@@ -588,7 +589,22 @@  mktime (struct tm *tp)
   __tzset ();
 #endif
 
-  return __mktime_internal (tp, __localtime_r, &localtime_offset);
+  return __mktime_internal (tp, __localtime64_r, &localtime_offset);
+}
+
+#ifdef weak_alias
+weak_alias (__mktime64, __timelocal64)
+#endif
+
+/* The 32-bit-time wrapper.  */
+time_t
+mktime (struct tm *tp)
+{
+  __time64_t t64 = __mktime64 (tp);
+  if (fits_in_time_t (t64))
+    return (time_t) t64;
+  __set_errno(EOVERFLOW);
+  return -1;
 }
 
 #ifdef weak_alias
diff --git a/time/timegm.c b/time/timegm.c
index fb720e2d7d..b554244a34 100644
--- a/time/timegm.c
+++ b/time/timegm.c
@@ -33,15 +33,27 @@ 
 # include <time_r.h>
 # undef __gmtime_r
 # define __gmtime_r gmtime_r
-time_t __mktime_internal (struct tm *,
-			  struct tm * (*) (time_t const *, struct tm *),
-			  time_t *);
+time64_t __mktime_internal (struct tm *,
+			  struct tm * (*) (__time64_t const *, struct tm *),
+			  __time64_t *);
 #endif
+# include <limits.h>
+# include <errno.h>
+
+__time64_t
+__timegm64 (struct tm *tmp)
+{
+  static __time64_t gmtime_offset;
+  tmp->tm_isdst = 0;
+  return __mktime_internal (tmp, __gmtime64_r, &gmtime_offset);
+}
 
 time_t
 timegm (struct tm *tmp)
 {
-  static time_t gmtime_offset;
-  tmp->tm_isdst = 0;
-  return __mktime_internal (tmp, __gmtime_r, &gmtime_offset);
+  __time64_t t64 = __timegm64(tmp);
+  if (fits_in_time_t (t64))
+    return (time_t) t64;
+  __set_errno(EOVERFLOW);
+  return -1;
 }